The present invention generally relates to information signal recording apparatuses, and more particularly to an information signal recording apparatus for recording information signals on an information signal recording disc rotated in a constant angular velocity mode or in a constant linear velocity mode, in which the apparatus is capable of adapting to the respective rotation mode of the information signal recording disc to provide an optimal recording.
It is well known that rotation mode of an information signal recording disc (referred to hereinafter as a disc) is generally classified into two categories, one of which is a constant linear velocity mode (referred to hereinafter as CLV mode) in which the disc is rotated in such a manner that a relative linear velocity between the disc and a pickup or a head is maintained at a constant value (such a disc will be referred to hereinafter as a CLV disc); and a constant angular velocity mode (referred to hereinafter as CAV mode) in which the disc is rotated in such a manner that a rotation speed of the disc is maintained at a constant value (such a disc will be referred to hereinafter as a CAV disc). The CLV mode is intented to achieve a longer recording and reproducing time as compared to the CAV mode and maintains the relative linear velocity between the disc and the pickup at a velocity corresponding to the linear velocity of a CAV disc at a vicinity of the innermost portion of an information signal recording area of the CAV disc. As a result, there is a problem that an upper frequency limit of an information signal to be recorded on a CLV disc cannot be selected as high as the upper frequency limit of the information signal recorded on a CAV disc. In other words, frequency range of the information signal to be recorded on a disc should be changed responsive to the type of the disc.
The applicant of the present invention proposed in Japanese Patent Application No. 60-223164, filed Oct. 7, 1985, a disc pre-recorded with a discrimination signal indicating whether the disc is a CAV disc or a CLV disc, and a discrimination circuit for discriminating whether the disc is a CAV disc or a CLV disc on the basis of the discrimination signal. According to the above Japanese patent application, the discrimination signal is recorded together with a rotation controlling signal on a single track which is separated from an information signal recording area of the disc. Thus, the information signal recording area of the disc is not reduced. As a result of the above Japanese patent application, there exist now possibilities that rotation controlling signal and other informations are obtained in a short time, and that a switching of a carrier frequency of a frequency modulator of the information signal recording apparatus as well as a switching of motor servo operation of the information signal recording apparatus can be achieved quickly and automatically responsive to the discrimination signal.
Accordingly, the object of the present invention is to provide a novel and useful information signal recording apparatus for recording information signals on an information signal recording disc.
Another and more specific object of the present invention is to provide an information signal recording apparatus for recording information signals on an information signal recording disc, in which the apparatus is capable of discriminating whether the information signal recording disc is a CAV disc or a CLV disc and having an arrangement to switch a carrier reference frequency of a frequency modulator of the information signal recording apparatus from one frequency corresponding to one of the discs to another frequency corresponding to another disc responsive to the result of the discrimination. The term carrier reference frequency used herein and hereinafter indicates a particular reference frequency defined in a frequency spectrum of the carrier to specify the frequency range of the carrier. The carrier reference frequency may be selected for example at a center frequency of the carrier or any other frequencies of the carrier which specify the particular portion of the frequency spectrum of the carrier such as a frequency corresponding to a tip end of a synchronizing signal hereinafter referred to as synctip. According to the information signal recording apparatus of the present invention, the problems aforementioned are solved by switching the carrier reference frequency of the frequency modulator to an optimal frequency responsive to the result of the discrimination indicating that the disc is a CAV disc or a CLV disc.
In those cases where the disc is discriminated to be the CAV disc, the carrier reference frequency of the frequency modulator is selected at a higher frequency which is chosen to enable the recording on the disc at the innermost portion of the recording area of the disc. On the other hand, in those cases that the disc is discriminated to be a CLV disc, the carrier reference frequency is switched to a frequency lower than the corresponding carrier reference frequency for the case of the CAV disc. As a result, the CAV disc can be recorded with an information signal having a relatively broad frequency range. Thereby, the carrier reference frequency is selected at the higher frequency which is chosen such that the recording is possible even at the innermost region of the information signal recording area of the CAV disc where the frequency range possible for recording is lowest. On the other hand, in those cases that the disc is a CLV disc, long time recording of the information signal can be achieved with an optimal frequency range which corresponds to the linear velocity of the disc relative to the pickup or head.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.